Ag/CuTb2O2 nanozyme-based dual-mode biosensor with self-validating function for ultrasensitive detection of organophosphorus pesticides.

In this study, a dual-mode electrochemiluminescent-colorimetric (ECL-colorimetric) biosensor based on Ag/CuTb2O2 nanozyme was developed for the ultrasensitive detection of trichlorfon and other organophosphorus pesticides (OPs) by inhibiting acetylcholinesterase (AChE). The Ag/CuTb2O2 composite, prepared via electrospinning and in-situ growth, exhibited high conductivity and superior peroxidase-like activity, acting as a dual-signal amplifier. In the ECL mode, it immobilized Ru(bpy)32+ and boosted the co-reactant pathway; in the colorimetric mode, it catalyzed H2O2-mediated oxidation of TMB. Based on AChE inhibition, trichlorfon reduced ECL intensity by decreasing thiocholine production and enhanced colorimetric signals by consuming thiocholine. This dual-signal self-validation improved detection reliability. The sensor achieved a linear range of 1 × 10-12-1 × 10-6 mol L-1 with LOD of 3.33 × 10-13 mol L-1 (ECL) and 30-5000 ng mL-1 with LOD of 10 ng mL-1 (colorimetric). It also responded to other OPs and gave satisfactory recoveries in vegetable samples, providing a reliable method for food safety monitoring.